1. Technical Field
The present invention relates to a touch panel, an electro optical device, and an electronic apparatus, and in particular to a structure of a touch panel equipped with a pair of opposing electrode films.
2. Related Art
An example of a general resistance type touch panel is shown in FIG. 12. In the touch panel shown in FIG. 12, a transparent electrode film 4 is formed on a first transparent substrate 1 in a flat manner. Further, a transparent electrode film 5 is formed on a second transparent substrate 2 disposed to have a distance with the first transparent substrate 1 in a flat manner so as to oppose the aforementioned transparent electrode film 4. The pair of transparent electrode films 4, 5 are normally oppositely disposed to each other to have a distance. When an outer surface of the second transparent substrate 2 is pressed by a finger, a touch pen, or the like, the pair of the transparent electrode films 4, 5 are made contact with each other by deflection occurred at the pressed position, and an output value corresponding to the contact position can be obtained.
The aforementioned touch panel is used in the state where overlapped and disposed at the viewing side of a display screen of any one of various electro optical devices such as a liquid crystal display body, so that the touch panel is required to have a high transmittance ratio. Consequently, in the past, it has been attempted to increase the transmittance ratio by forming a reflection preventing film on the substrate or on the transparent electrode film (for example, see JP-A-7-257944, JP-A-2002-222056).
Further, it has been known to provide openings in the transparent electrode film of the resistance type touch panel in order to adjust a resistance value of the transparent electrode film (for example, see JP-A-2001-154791, JP-A-62-190524).
However, in the aforementioned touch panel, only the light reflected at a surface or a boundary face of the substrate or the transparent electrode film is reduced even when the reflection preventing film is provided, and the transmittance ratio itself of the transparent electrode film itself is not reduced. Accordingly, there was a limit to improve the transmittance ratio as a touch panel, and there was a problem in that it was difficult to illuminate a display image of the electro optical device disposed behind the touch panel.
Further, each of the opposing surfaces of the aforementioned pair of the transparent electrode films formed by a normal sputtering method becomes an extremely flat surface and becomes a mirror surface state. Consequently, there were also problems in that the transparent electrodes were stuck together when pressed by a finger or a touch pen, and noise was generated when the pair of stuck transparent electrode films was unstuck.